Abstract
In this paper (Part II of a paper series), a 3D pseudo-potential lattice Boltzmann method in combination with a solid-liquid phase change model with volume expansion taken into consideration (the same model used in Part I) is applied to study a water droplet's impact and its subsequent freezing patterns on rough supercooled substrates, consisting of an array of micro-pillars in a saturated vapor environment. Freezing patterns of the droplet in three different modes on rough surfaces depending on the contact angle are investigated. In the Hemi-wicking Cassie-Baxter mode where the water droplet fills into grooves between micro-pillars completely, heat conduction rate increases because of the increasing contact area of the water droplet and the micro-pillars, and the contact angle becomes smaller which results in the central-concave icing pattern. When the droplets are in the Wenzel mode and the Cassie-Baxter mode on the rough surface, saturated vapor exists between the droplet and the micro-pillars, which brings additional thermal resistance between the supercooled substrate to droplets. This results in lower heat conduction rate which delays ice nucleation time and allows the droplet to complete its recoiling motion that leads to the formation of the central pointy icing pattern. Because static contact angles of rough substrates in these two modes are higher than those of the corresponding smooth substrates, droplets’ recoiling motions on rough substrates are stronger which lead to the formation of central-pointy icing patterns. Regime maps, showing effects of contact angle and Stefan number on formation of central-pointy icing or central-concave icing patterns of a water droplet (with D0 = 100 and Pr = 13.5) after its impact on rough substrates at supercooled temperatures at We= 320 and Re = 164.9 are presented.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
